For many years, attempts to adapt two cycle internal combustion engine concepts to replace conventional multi-cylinder four cycle applications have met with failure. Some, but not necessarily all, of the causes for these failures are (a) excessive and uncontrollable exhaust emissions which result in completely unacceptable amounts of atmospheric pollution's; (b) very short operational life (typically approximately 20%) due primarily to common and typical two cycle engine designs; (c) the necessity to use combustion air to carry fuel as well as lubricating oil into the combustion chamber which creates a myriad number of problems for many operators.
Proof of these totally unacceptable conditions (among many others) has been published in newspapers throughout the world and by virtually all the major manufactures of automobile engines.
This invention overcomes all of the existing shortcomings of present day two cycle engine configurations, especially those mentioned above and provides a practical, efficient, clean-burning, power source for virtually all internal combustion engine requirements throughout the world. All with cost savings of about 50% of present day four cycle engine applications.
Today's four-cycle internal combustion engines are marvelous and fantastic results of millions of dollars and engineering hours of development, design and materials applications. Equipment and processes have been continually improved for the last 100 years and, with the cooperation of the chemical and petroleum industries, the public today drives vehicles with internal combustion multi-cylinder engines with 100,000 (or more) miles of life warranties.
This two cycle engine concept retains every one of these improved materials and manufacturing processes and with (among other) advantages: engines will have (a) approximately one half of the weight; (b) approximately one half of the physical size; (c) approximately one half of the cost; and (d) virtually no changes in present day materials and manufacturing facilities, process and equipment.
For example, in today's automotive market, the six-cylinder "V" configuration engine is utilized very extensively. Retaining physical dimensions of bore and stroke, horse power and torque, and all other amenities, this six-cylinder engine could be replaced with a three cylinder two-cycle engine using the same engine components, and still retain all the engine statistics available in the four-cycle configuration.
In every four-cycle engine, only one half of the cylinders produce power strokes for each 360.degree. rotation of the crankshaft. The "idle" remaining cylinders are USING energy, exhaling exhaust gases or inhaling fresh air.
In this two-cycle engine concept, each and every cylinder/piston unit produces a power stroke for each 360.degree. rotation of the crankshaft. The functioning of a two-cycle engine is known in the art but will be repeated here to provide a basis to understand the invention disclosed herein.
1. Fuel is injected into the cylinder early in the air compression portion of the upward travel of the piston. Note: combustion air had been supplied to the cylinder as described later.
2. Air and fuel (fuel supply controlled by the throttle control position and associated electronic circuitry) are further compressed until the piston reaches top dead center.
3. At the appropriate time, electronically controlled ignition occurs and the piston produces its power stroke.
4. As the piston approaches the bottom of its stroke, combustion has ceased and the extreme pressures within the cylinder have abated. The exhaust valve(s) starts to open (the lower tappet arms may also be moved by means of metal actuating arms attached to the connecting rod instead of the extensions added to the piston skirt) and pressure in the cylinder is reduced almost to atmospheric pressure as the exhaust gases are expelled into the exhaust manifold and to the exhaust control system.
5. Within a few more degrees of crankshaft rotation the intake valve(s) start to open (the lower tappet arms may also be moved by means of metal actuating arms attached to the connecting rod instead of the extensions added to the piston skirt) and fresh air (under pressure) enters the cylinder, as described later.
6. Since both valves are now open, fresh air continues to enter the cylinder and, of course, some of the fresh air exits via the open exhaust valves. This action will continue until both the exhaust and intake valves close. Fresh air through the cylinder exiting into the exhaust system will purge the cylinder of any remaining exhaust products.
7. As the piston starts its compression stroke both valves will close and the compression cycle will start.
As described above, the function of a two-cycle engine begins with combustion air (under pressure) entering the cylinder from the intake manifold and via the intake valve(s). Fuel is then injected into the cylinder after the exhaust and the intake valves are closed. The fuel/air mixture is compressed, and ignition of the compressed fuel/air mixture is performed while the piston is at the top of its stroke. The products of combustion are released into the exhaust system via the conventional exhaust valves.
As is known, in conventional four-cycle engines, intake and exhaust valves have been predominantly operated by tappet arms, which in turn have been operated by a combination of timing gears, timing belts and cam shafts. Other systems which use solenoids and hydraulics have not proven satisfactory to operate intake and exhaust valves.
The combinations of cam shafts and gears used in four-cycle engines have been refined extensively but are not suitable for two cycle operation. Furthermore, these components are some of the most expensive parts of modern internal combustion engines.
Modern valves in the cylinder head (the number of valves per cylinder does not affect this invention), open by means of tappet arms pressing on the ends of valve stems and are closed by valve springs when the tappet arms are released by the cam shaft and associated mechanisms.
The valves in this two-cycle engine are also operated by tappet arms of a slightly different design. Instead of the vertical motion being imparted by the camshaft, the tappet or rocker arm is caused to move by means of a push (or pull) rod. This push (or pull) rod [depending on design] is, in turn connected to a second tappet arm, (somewhat similar to the upper tappet arm) but its fulcrum bearing is fastened to the lower cylinder block (or to a support bracket), at the bottom of the cylinder block.
One arm of the lower tappet arm extends into the area of the cylinder bore enough to be contacted by a hardened extension of the skirt of the piston. Thus, before the piston reaches bottom dead center, the extension built into the piston skirt (or attached thereto) will contact the lower tappet arm opening or closing valves as needed.
As such, it is an object of the present invention to provide a two-cycle combustion engine which:
1. Embodies means to operate air intake and exhaust valves to emulate the functions of the air intake and exhaust ports, which are used in virtually all present day two-cycle engines;
2. The number of air intake and exhaust valves per function and per cylinder is limited only by design;
3. Valve timing is consistently precise;
4. Valve life is limited only by available designs and technology;
5. No unique or exotic design or construction conditions are required;
6. Allows for the use of a standard fuel injector; and
7. Allows for the lubricating oil to be in the crank case as opposed to in the fuel which is normal for a two-cycle engine.